The invention relates to communication networks, and in particular to methods and apparatus for tracing soft permanent virtual circuit connections.
Asynchronous Transfer Mode (ATM) technologies have been developed to derive combined benefits from packet-switched technologies and circuit-switched technologies. Packet-switched technologies benefit from an efficient utilization of bandwidth. Circuit-switched technologies benefit from a high quality-of-service. ATM technologies employ fixed sized packets, known as cells, which are switched in an ATM network to follow Virtual Circuit (VC) transport paths.
FIG. 1 is representative of an ATM network 100 which includes ATM network nodes 102 and interconnecting links 104. Legacy ATM cell transport includes the use of pre-established Permanent Virtual Circuits (PVCs) 106 in the ATM network 100 provisioned over selected interconnecting links 104. The establishment of a PVC 106 is performed by a call manager entity 110 which has access to knowledge regarding: the topology of the managed ATM network, cell processing capacities of each managed network node, transport bandwidth capacities of each: managed interconnecting link, etc. The call manager 110 makes use of a network configuration database 112 to store and track provisioning information about the network 100.
If a connection is needed between any two ATM network nodes 102, a request 120 for establishing the connection is provided to the call manager 110. The request 120 includes a network address specification corresponding to the source network node 102-S requesting the establishment of the connection and a network address specification corresponding to the destination network node 102-D. The request may also specify resource utilization requirements including, but not limited to: a required average bandwidth, a maximum transport latency, a maximum jitter, etc.
The call manager 110, upon receiving the request 120 for establishing a connection, parses the request 120 to extract the source and destination network node addresses, and the resource utilization requirements. Based on the extracted information, and information held in the network configuration database 112, the call manager 110 attempts to determine 122 a transport path, of network nodes 102 and interconnecting links 104, which will have enough spare cell processing capacity at the network nodes 102, and enough transport bandwidth on the interconnecting links 104, to accommodate the new connection in the network 100. Once the transport path is determined 122, various commands are sent, via signaling messages 124, to the network nodes 102 in the transport path to reserve resources for PVC 106 to be established therebetween. Once all network nodes 102 in the transport path confirm the resource reservations, via return setup complete signaling messages 126, the PVC 106 is said to be established. The call manager 110 also updates 128 the network configuration database 112 with the particulars of the new PVC transport path.
Via a Network Management System (NMS) 140, network administrators 130 may be provided with a visual display 132 of all PVCs 106 in use in the network 100. The provisioning of the visual display 132 is possible due to the fact that all PVC transport path provisioning information is available centrally via the network configuration database 112. The availability of PVC transport path information stored in the network configuration database 112 enables micro-management of network resources.
Should any network infrastructure failures occur, network nodes 102 connected to the affected failed interconnecting links 104 or failed network nodes 102, inform the call manager 110 thereof, via signaling messages (not shown). The call manager 110 updates 128 the network configuration database 112 to reflect the failed equipment, determines the PVCs 106 which were provisioned via the failed network infrastructure, and the call manager 110 begins to reprovision (122, 124, 126, 128) all the affected PVCs 106 around the failed network infrastructure one-by-one in the same fashion presented above. Besides the deleterious effects of the infrastructure failure, a large amount of bandwidth is needed for the conveyance of signaling messages 124/126/128 to effect the reprovisioning of the affected PVCs.
A person of ordinary skill in the art understands that ATM technologies were devised to provision a large number of PVCs 106 in order to deliver high transport capacities. An infrastructure failure therefore affects a large number of PVCs 106 which the call manager 110 will have to reroute in a short period of time following the infrastructure failure to reduce cell loss.
There has been a trend towards conveying cells at ever increasing transport bandwidths over the interconnecting links 104, and employing network nodes 102 of higher and higher cell processing capacities. The processing requirements imposed on the call manager 110 can quickly stress the call manager entity to its processing limits especially when network failures occur. As the call manager 110 is associated with a network node 102-CM, an abnormal amount of signaling traffic processing is experienced by the network node 102-CM although the network node 102-CM may not be closely associated with the failed network infrastructure. The sequential transport path re-determination in healing the affected network 100 is considered very slow and typically leads to excessive cell loss.
In referring to FIG. 2, recent developments have brought about intelligent ATM network nodes 202 which led to intelligent networks 200. Intelligent ATM network nodes 202 use Private Network-Node Interface (PNNI) signaling to perform some of the tasks related to connection establishment, and connection rerouting in response to network failures. The transport path determination and reconfiguration performed by the intelligent network nodes 202 themselves, is enabled via the use of Soft Permanent Virtual Circuits (SPVC) 206. In the event of a network failure 208, benefits are derived from parallel transport path rerouting 210 which reduces the probability of cell loss. The use of SPVCs 206 provides connectivity resiliency by distributing SPVC connection re-routing processing overheads over many intelligent network nodes 202 in the network 200. For this reason SPVCs are also know colloquially as Smart PVCs.
In using SPVCs 206 to provision connectivity, the call manager 110 only keeps track of SPVC connectivity states at a high levelxe2x80x94the task of ensuring low level physical SPVC connectivity being performed by the intelligent network nodes 202 themselves. The result is that the call manager 110 is informed 226 of the establishment of SPVCs 206 but not of the transport path used by the SPVCs. Therefore, in using SPVCs 206, the call manager 110 and the network configuration database 112, no longer have access to detailed connectivity information. Network administrators 130 can only engage in macro-management of network resources because the visibility of detailed connectivity information is diminished compared to what was previously enjoyed by using PVCs. As a result there is a reluctance to employ SPVCs 206 in provisioning connections over ATM infrastructure.
There is a strong demand to provide SPVC configuration visibility akin to PVC provisioning to enable micro-management of SPVC connections.
An extension to PNNI signaling has been described in af-cs-0141.000, xe2x80x9cPNNI Addendum for Path and Connection Tracexe2x80x9d, Version 1.0, March 2000, which is incorporated herein by reference. Provisions are made for SPVC path tracing in troubleshooting connection establishment, and for SPVC connection tracing for discovering the transport path used by already established SPVC connections.
The very recent adoption of the af-cs-0141.000 extension to PNNI signaling has only benefited from a limited implementation. Prior art implementations enable a network administrator 130 to manually select 230, via a network management system 140 having access to the network configuration database 112, a single SPVC connection, and to manually issue a single SPVC connection trace command 232 to a single source trace node 202-S. The SPVC trace results are provided via a trace transit list and stored at the source trace node 202-S. The network administrator 130 needs to manually connect to the source trace node 202-S via an element management interface, manually retrieve the trace transit list, and interpret it. This implementation is inadequate in providing network-wide visibility of all active SPVC connectivity because of the large number (millions) of SPVCs 206 typically intended to be used.
There therefore is a need to address the above mentioned issues.
In accordance with an aspect of the invention, a bulk SPVC connection trace processor is provided. The bulk SPVC connection trace processor includes an information store, an accumulator, a dispatcher, and a collector. The information store tracks SPVC connection status change reports for a plurality of SPVC connections. The accumulator gathers a group of SPVC connection status change reports. The dispatcher is triggered by the accumulator to initiate the issuance of a plurality of SPVC connection trace commands to trace source network nodes corresponding to SPVC connections associated with in the group of SPVC connection status change reports. The collector accesses the trace source network nodes to retrieve trace transit list information and provides consolidated SPVC transport path information derived from the retrieved trace transit list information. The tracking of SPVC connection status change reports provides a dynamic response to SPVC connectivity changes in a managed network.
In accordance with another aspect of the invention, the bulk SPVC connection trace processor further includes a control interface to receive SPVC connection tracing requests for a selection of SPVC connections.
In accordance with a further aspect of the invention, a method of tracing a plurality of SPVC connections is provided. Received SPVC connection status change reports corresponding to a multitude of SPVC connections are tracked. A group of received SPVC connection status change reports is accumulated. SPVC connection tracing commands are dispatched to a group of trace source network nodes provisioning SPVC connections corresponding to the group of accumulated SPVC connection status change reports. And, trace transit list information is collected from the group of trace source network nodes. The tracking of received SPVC connection status change reports provides a dynamic response to SPVC connectivity changes in a managed network.
In accordance with yet another aspect of the invention, the trace transit list information for each traced SPVC is stored to provide connectivity information akin to that typically available for PVCs.
The advantages are derived by network administrators, higher network management and service provisioning functions, being provided with the same level of transports path information detail previously enjoyed in using PVCs. Network planning and design functions previously built for PVC provisioning may be seamlessly upgraded in migrating to SPVC connectivity.
By engineering the execution of bulk SPVC connection tracing, a minimized effect is felt by the network management and service provisioning tasks, enabling a large number of SPVC connections to be traced and thereby removing a major roadblock to large scale SPVC deployment.